In semiconductor devices, wiring between a semiconductor element (chip) and a lead wire or a circuit substrate has been carried out by wire bonding using an aluminum (Al) wire, and an aluminum wire is connected to an aluminum or gold material formed on a surface of an electrode of the semiconductor element.
For power sources of, for example, domestic electric appliances, OA equipment, audio apparatuses, etc., power semiconductor devices (for power control) such as diodes and transistors are used, and also in these power semiconductor devices, an aluminum wire is used as a metallic wire for wire bonding due to demands for a high-voltage current and cost reduction as shown in, for example, JP 6-260538 A.
On the other hand, recently wire bonding using a copper wire which is advantageous from the viewpoint of thermal conductivity, electric conductivity, etc. has been proposed as shown in CIPS 2010, Mar. 16-18, 2010, Nuremberg/Germany—Paper 3.7, in which a copper wire is connected to an aluminum or copper material formed on a surface of an electrode of a semiconductor element. Generally there are a small diameter copper wire and a large diameter copper wire. In the case of a small diameter copper wire, one having a diameter of less than 75 μm is used for wiring by ball bonding technology, and an aluminum material is used on a surface of an electrode of a semiconductor element. In the case of a large diameter copper wire, one having a diameter of not less than 75 μm is used for wiring by wedge bonding technology, and a copper material is used on a surface of an electrode of a semiconductor element.